There has been a long existing need in the prior art for a wiring device of the housewiring type which can be installed by mounting against a stud or alternatively in an opening of a wallboard where a stud is not present. There have been various structures in the prior art which accomplish wallboard mounting. One example involves a two-piece wiring device wherein a first portion is located in a wallboard opening from the front side of the wallboard and a second portion is assembled to the first portion from the back side of the wallboard. In another exemplary structure, a wiring device is inserted into a wallboard opening from the front side wherein deformable or pivotable portions on the back side of the wiring device are spread outwardly into registration with the back side of the wallboard. In such structures it is necessary for an installer to have access to the back side of a wallboard such that installation operations can be performed. Often, however, access to the back side of a wallboard is not available, for example wherein replacement of a defective or worn wiring device would require damage to the wallboard in order to obtain access to the back side thereof. Often it is desirable to install an additional wiring device to a wiring system already installed behind a wallboard. Under such a situation it would be advantageous to install a wiring device which is structured and designed to eliminate the need for access to the back side of the wallboard.